Check the c clip at the end of the axle it could be worn out from when the kit was installed or it could have popped off. Install a new clip and see what happens.
while you have the axle out make sure the CVs are clocked correctly . most likely its the C clip . but alot of people dont think about the clocking of the CVs and under extreme angle it puts them in a bind and can cause them to pop out.
what its doing is when its all together I go to tighten the axle nut
it pulls the cv right out the diff almost as if the axle is a little to short I checked the axles and they are right so just not sure
I agree with Court,make sure your frt diff has not moved because the mounts are weak.Also make sure the inner cv is plunging all they way in and out otherwise your axle is to short.